字母和数字依次出现的密码生成器

随机重新排列 pass1 和 pass2 元素（参见此处或此处），然后使用 linq 的 Zip 并借助 .Take所需的字符数进行剪切。

例如：

void Main()
{
    string pass1 = "123456789";
    string pass2 = "QWERTYUIOPASDFGHJKLZXCVBNM";
    this.GenPass(pass1.Shuffle(), pass2.Shuffle(), 10).Dump();
}

public string GenPass(string pass1, string pass2, int maxChar)
{
    var result = pass1.Zip(pass2, (x, y) => $"{x}{y}");
    //result.Dump();
    var joined = string.Join("", result).Take(maxChar);
    return new string(joined.ToArray());
}

public static class Ext1
{
    public static string Shuffle(this string str)
    {
        char[] array = str.ToCharArray();
        Random rng = new Random();
        int n = array.Length;
        while (n > 1)
        {
            n--;
            int k = rng.Next(n + 1);
            var value = array[k];
            array[k] = array[n];
            array[n] = value;
        }
        return new string(array);
    }
}

或许有什么需要改进的地方，刚刚解决了“额头上”的问题。

我写了一个笨拙但简单易懂的解决方案：

  // строки, содержащие нужные символы
  static string numbers = "123456789";
  static string letters = "QWERTYUIOPASDFGHJKLZXCVBNM";

  static char generate_random_letter() {
    return letters[rnd.Next(letters.Length)];
  }

  static char generate_random_number() {
    return numbers[rnd.Next(numbers.Length)];
  }

  public static void Main (string[] args) {
    int password_length = 10;
    string password = "";

    for (int i = 0; i < password_length; i++) {
      if (i % 2 == 0) {
        password += generate_random_letter();
      }
      else {
        password += generate_random_number();
      }
    }

    Console.WriteLine(password);
  }

下面的示例限制为 18 个字符（可以扩展）。

  static String GetRandomPass(Int32 length) {
    if (length > 18) return null;

    Random r = new Random();
    String p = String.Join("",
      Enumerable.Range(65, 26).OrderBy(a => r.Next()).Zip(
        Enumerable.Range(49, 9).OrderBy(b => r.Next()),
        (x, y) => new String(new Char[]{(Char)x, (Char)y})
    ).ToArray());

    return p.Substring(0, length);
  }

我们都知道在这些事情上不需要漂亮、正确和可读的代码。您需要一个 LINQ 单行代码，您可以不经意间将其复制到代码中并立即发送到生产环境。

实际上，这里是：

int length = 12;  // длина
var random = new Random();
var result = string.Join("",Enumerable.Range(0, length).Select(i => i%2==0 ? (char)('A'+random.Next(26))+"" : random.Next(1, 10)+""));

好吧，或者与解释相同：

var result = string.Join("",                                // создаем строку
    Enumerable.Range(0, length)                             // из последовательности длины length
                .Select(i =>                                 
                    i%2==0 ?                                // на четных местах
                        (char)('A'+random.Next(26))+"" :    // генерируем букву
                        random.Next(1, 10)+"")              // на нечетных цифру
                );

使用Random rnd = new Random(0);？

Random必须使用，但必须使用空的构造函数。采用数字 ( Random (int Seed)) 的构造函数使用该数字作为初始状态。这Random将始终产生相同的数字序列。

PSpass1并pass2没有使用它，而是生成英文字母的大写字母和 1 到 9 的数字（顺便说一下，为什么不使用 0？）。

    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using System.Threading;

    namespace Rextester
    {    
        public enum PasswordWeakLevel
        {
            NotDefined,
            VeryWeak,
            Weak,
            Sufficient,
            Strength,
            Resistant,
            VeryResistant
        }

        public static class PasswordUtils
        {
            private static int MaxRepeatsChar = 2;

            public static string GenerateStrongPass(int PassLength = 7, bool UsePunctuation = true, bool UseEntropy = true, int CheckDigits = 0)
            {
                int checkSum = 0;
                Random randC = new Random();
                string result = char.ToString((char)randC.Next(65, 90));

                List<char[]> Intrvs = new List<char[]>();

                char[] charr;
                if (UsePunctuation)
                {
                    string specChars = @"!#$%&*+-/=?@\^_|~";   //@"!#$%&()*+-/;<=>?@[\]^_{|}~";
                    charr = specChars.ToCharArray();

                    Intrvs.Add(charr);
                }

                string gl = "AaEeIiOoUu";
                charr = gl.ToCharArray();
                Intrvs.Add(charr);

                string sl = "BbCcDdFfGgHhJjKkLMmNnPpQqRrSsTtVvWwXxYyZz";
                charr = sl.ToCharArray();
                Intrvs.Add(charr);

                string dl = "189647235";
                charr = dl.ToCharArray();
                Intrvs.Add(charr);

                Random randI = new Random();

                while (result.Length < PassLength)
                {
                    int rndIndex = randI.Next(Intrvs.Count);
                    int charIndex = randC.Next(Intrvs[rndIndex].Length);

                    string C = char.ToString(Intrvs[rndIndex][charIndex]);

                    if (!result.Contains(C) && (result.Length < 35))
                    {
                        result += C;
                    }
                    else
                    if (!UseEntropy)
                    {
                        result += C;
                    }
                }

                if (CheckDigits > 0)
                {
                    int i = 1;
                    int last = 719;
                    foreach (var c in result)
                    {
                        checkSum += (Convert.ToInt32(c) * i) + last;
                        i++;
                        last = Convert.ToInt32(c);
                    }

                    string hex = ((checkSum / Convert.ToInt32(result[0])) * 2).ToString("X2") + checkSum.ToString("x2");
                    int checkCounts = hex.Length;
                    result += hex.Substring(hex.Length - CheckDigits, Math.Min(CheckDigits, checkCounts));
                }

                return result;
            }

            public static PasswordWeakLevel TestPasswordWeak(string password, string login)
            {
                var _res = PasswordWeakLevel.NotDefined;

                if (!IsPasswordLikeLogin(password, login) && !IsQwertyPasswords(password))
                {
                    if (password.Length > 5)
                    {
                        if (ContainsUpperLetter(password) && ContainsLowerLetter(password)) _res = PasswordWeakLevel.Weak;
                        if (ContainsDigit(password)) _res++;  //Sufficient

                        if (RepeatSigns(password)) _res--;
                        if (IsStriping(password)) _res++;  //Strength

                        if (ContainsPunctuation(password) && ContainsSeparator(password)) _res++; //Resistant
                        if ((_res == PasswordWeakLevel.Resistant) && (password.Length > 15)) _res++;
                    }
                    else
                        _res = PasswordWeakLevel.VeryWeak;
                }
                return _res;
            }

            private static bool IsQwertyPasswords(string pass)
            {
                var keyboardlist = new List<string>();
                keyboardlist.Add("azer");
                keyboardlist.Add("qwer");
                keyboardlist.Add("asdf");
                keyboardlist.Add("zxcv");
                keyboardlist.Add("1234");

                foreach (string item in keyboardlist)
                {
                    if (pass.ToLower().Trim().Contains(item.ToLower()))
                        return true;
                }
                return false;
            }

            private static bool IsPasswordLikeLogin(string pass, string login)
            {
                if (login != string.Empty)
                {
                    if (login.ToLower().Trim().Contains(pass.ToLower().Trim()) || pass.ToLower().Trim().Contains(login.ToLower().Trim()))
                    {
                        return true;
                    }

                    string reversed = "";
                    char[] passarr = pass.ToCharArray();

                    for (int i = pass.Length - 1; i >= 0; i--)
                    {
                        reversed = reversed + passarr[i];
                    }

                    if (reversed.ToLower().Trim().Contains(login.ToLower().Trim()))
                    {
                        return true;
                    }
                }

                return false;
            }

            private static bool RepeatSigns(string pass)
            {
                char lastchar = (char)0;
                int _rep = 0;
                foreach (char c in pass)
                {
                    if (lastchar == c)
                    {
                        _rep++;
                        if (_rep > MaxRepeatsChar)
                            return true;
                    }
                    lastchar = c;
                }
                return false;
            }

            private static bool IsStriping(string pass) // фактор перемеживание букв и символов
            {
                int stripcount = 0;
                char lastchar = (char)0;
                foreach (char c in pass)
                {
                    if ((Char.IsLetterOrDigit(c) && ((Char.IsLetter(c) && Char.IsDigit(lastchar)) || (Char.IsDigit(c) && Char.IsLetter(lastchar)))) ||
                       ((Char.IsLetterOrDigit(c) && !Char.IsLetterOrDigit(lastchar)) || ((Char.IsLetterOrDigit(lastchar) && !Char.IsLetterOrDigit(c)))))
                    {
                        stripcount++;
                        if (stripcount > pass.Length / 3)
                            return true;
                    }
                    lastchar = c;
                }
                return false;
            }

            private static bool ContainsLowerLetter(string pass)
            {
                foreach (char c in pass)
                {
                    if ((Char.IsLetter(c)) && (Char.IsLower(c)))
                        return true;
                }
                return false;
            }

            private static bool ContainsUpperLetter(string pass)
            {
                foreach (char c in pass)
                {
                    if ((Char.IsLetter(c)) && (Char.IsUpper(c)))
                        return true;
                }
                return false;
            }

            private static bool ContainsDigit(string pass)
            {
                foreach (char c in pass)
                {
                    if (Char.IsDigit(c))
                        return true;
                }
                return false;
            }

            private static bool ContainsPunctuation(string pass)
            {
                foreach (char c in pass)
                {
                    if (Char.IsPunctuation(c))
                        return true;
                }
                return false;
            }

            private static bool ContainsSeparator(string pass)
            {
                foreach (char c in pass)
                {
                    if (Char.IsSeparator(c))
                        return true;
                }
                return false;
            }

            public static bool BadPasswordSecurity(string pass, string Login)
            {
                return ((int)PasswordUtils.TestPasswordWeak(pass, Login) < 5);
            }
        }
        static class Program
        {
            /// <summary>
            /// The main entry point for the application.
            /// </summary>
            public static void Main(string[] args)
            {
              for(int i = 0; i< 100; i++)
              {
                  string pass = PasswordUtils.GenerateStrongPass(11, true, true, 0);
                  Console.WriteLine(pass);
                  Thread.Sleep(100);
              }
            }
        }
    }